To increase the difficulty of a curl-up, what action should be taken?

To effectively increase the difficulty of a curl-up, positioning the hands behind the head enhances the challenge of the exercise. This adjustment requires greater engagement of the core muscles and the hip flexors because it introduces an added load and an increased range of motion. When the hands are placed behind the head, individuals must exert more effort to stabilize their torso and perform the curl-up movement, thereby intensifying the overall workout.

Additionally, this hand position can promote better alignment and control throughout the movement, which is beneficial for developing strength in the abdominal muscles. This contrasts with having the hands beside the body, which tends to make the exercise easier and less challenging for core engagement.